The nucleus accumbens and certain of its putative neurotransmitters (e.g., dopamine an acetylcholine) have been implicated in the etiology of schizophrenia. The goal of the proposed project is to determine the electrophysiological effects of dopamine, acetylcholine, and certain phenothiazines with respect to neuronal excitability in the nucleus accumbens. In particular, effects upon different cell populations will be contrasted. For example, the effects of dopamine on cells which monosynaptic hippocampal input with those effects on cells which monosynaptic lateral pre-optic input. Additionally, the effects of chloropromazine (with marked extrapyramidal effects) and thioridazine (without marked extrapyramidal effects) will be contrasted. Rabbits, acutely prepared under various anesthetic conditions, will serve as subjects. Field and extracellular unitary potentials following microstimulation of the fimbria, lateral pre-optic area and cell groups A10 will be challenged by the iontophretic administration of the substances.